Ran across a little Thomas compressor (12VDC). Model 315CDC56/12H
Price seems pretty decent, but its over 13 years old and its been used.
I've got a knockoff that looks similar behind the seat of my 2500HD 4x4 now and it works pretty good after I got rid of the little toy cables and put some decent size cables on it.
Anyway, Thomas is one of the "good" brands, and I was thinking if its ok I might toss the knock off in my work truck and put the Thomas in my 4x4.
Figured you serious hard corps 4x4 guys would know...